THE COMMERCIAL PILOT MADE A PRECAUTIONARY LANDING AT A CLOSED AIRPORT NEAR HIS DESTINATION AFTER OBSERVING AN ENGINE OIL PRESSURE LOSS. AFTER LANDING, AN INSPECTION OF THE AIRCRAFT DID NOT REVEAL ANY EVIDENCE OF AN OIL LOSS, AND A SUBSEQUENT ENGINE RUN ON THE GROUND SHOWED NORMAL OIL PRESSURE INDICATIONS. THE PILOT CONCLUDED THAT THE OIL PRESSURE INDICATING SYSTEM WAS AT FAULT, AND ELECTED TO CONTINUE TO HIS DESTINATION. HE PERFORMED A SHORT FIELD TAKEOFF DUE TO A SHORT RUNWAY LENGTH AND DEPARTURE END OBSTRUCTIONS (TREES). AT TAKEOFF SPEED, THE AIRCRAFT WOULD NOT ROTATE, AND THE PILOT ELECTED TO ABORT THE TAKEOFF. HE COULD NOT STOP THE AIRCRAFT IN THE REMAINING RUNWAY DISTANCE, AND THE AIRCRAFT COLLIDED WITH THE TREES. NO EVIDENCE OF A MECHANICAL MALFUNCTION OR FAILURE WAS FOUND. THE PILOT REPORTED THAT THERE WAS NO LOSS OF ENGINE POWER DURING THE TAKEOFF ROLL.